Tire and wheel assemblies

ABSTRACT

A pneumatic tire and wheel assembly including a single chamber pneumatic tire in which is provided a flowable liquid lubricant to facilitate relative movement between the internal surface of the tire which come into contact when the tire is run under load in the deflated condition, of which the following is a specification.

United States Patent 1 Powell et al.

[ TIRE AND WHEEL ASSEMBLIES [75] Inventors: Leslie Vernon Powell;Reginald Harold Edwards, both of Birmingham, 24, England [73] Assignee:Dunlop Holding Limited, London,

England [22] Filed: June 18, 1971 [2]] App]. No.: 154,326

[30] Foreign Application Priority Data June 20, 1970 Great Britain30,033/70 Apr. 3, 1971 Great Britain 8,592/71 [52] US. Cl. 152/330 [51]Int. Cl. B60c 5/00 [58] Field of Search 152/330 V, DIG. 5,

[ June 19, 1973 [5 6] References Cited UNlTED STATES PATENTS 3,628,58512/1971 Pace 152/347 2,316,549 4/1943 Benson 152/330 PrimaryExaminerJames B. Marbert Attorney-Stevens, Davis, Miller & Mosher [57]ABSTRACT A pneumatic tire and wheel assembly including a single chamberpneumatic tire in which is provided a flowable liquid lubricant tofacilitate relative movement between the internal surface of the tirewhich come into contact when the tire is run under load in the deflatedcondition, of which the following is a specification.

15 Claims, 1 Drawing Figure TIRE AND WHEEL ASSEMBLIES This inventionrelates to tire/wheel assemblies.

Upon partial or complete deflation of a pneumatic tire mounted on awheel during the running of a vehicle opposite surfaces in the interiorof the tire and wheel assembly come into contact with one another undermore or less load according to whether or not deflation is complete,considerable heat is generated within the rubber and textile componentsof the tire and very rapid structural failure ensues.

One approach to this problem in the past has been to provide a second,independent, air chamber inside the tire so that if the tire ispunctured the second chamber remains inflated and prevent the tire fromcollapsing and running on the rim. The disadvantages of this type ofconstruction are that it is expensive and adds weight to the tire andhence adds to the unsprung weight of a vehicle on which it is used. Agrave problem is also that the inner chamber chafes on the interior ofthe outer chamber of the tire even, in the bead region at least, duringnormal running of the tire. To combat this problem it has been proposedto lubricate the surface of the inner chamber and/or inner surface ofthe outer chamber with a suitable coating. Low profile tires e.g. ofaspect ratio v30 percent to 75 percent present a further problem in thatthe low sectional height allows little height for an inner chamber toprevent the tire bottoming on the rim.

The regions of the interior surfaces of a single chamber pneumatic tirewhich normally come into contact when running in the deflated conditionare the interior surfaces of the tire close to but radially outwardly ofthe rim flange and the interior surfaces of the tire close to butradially-inwardly of the tread edge. It has been discovered that themajor source of the heat generated which leads to the failure of thetire, is the relative movement of the interior surfaces of the tirewhich are in contact and under load.

According to the present invention a pneumatic tire and wheel assemblycomprises a single chamber pneumatic tire wherein aflowable liquidlubricant is provided for the lubrication of the interior surfaces ofthe tire whereby in use of said assembly with the tire in a deflated orsubstantially under-inflated condition the relative movement between theinterior surfaces of the tire in contact with one another isfacilitated.

The liquid lubricant preferably is miscible with water so that leakagefrom a tire and wheel assembly onto a road surface can be washed awayalthough a water insoluble lubricant can be used if desired. It is alsodesirable that the lubricant should not freeze at temperatures above Cso as to withstand cold weather. The liquid lubricant may have a boilingpoint of at least 90 C and preferably, in order to withstand hightemperatures without severe loss through volatilization a liquidcomponent of the lubricant has a vapor pressure of less than 50 mm ofmercury at 140 C.

The liquid lubricant advantageously has a viscosity which is as high asis practicable to minimize lubricant loss through a puncture and assistin sealing a puncture bearing in mind the need for the lubricant to flowinto the portions of the tire interior requiring lubrication. Thepreferred viscosity range for the liquid lubricant is 10,000 to 200,000centistokes at 38 C. Preferably also the lubricant although having ahigh viscosity has a low resistance to shear i.e. is a thixotropicmaterial.

The liquid lubricant preferably has no deleterious effect on the rubberor other component of the tire carcass. If desired liquid lubricantswhich normally swell or otherwise affect rubber could be used by the useof a special impervious protective inner liner in the tire.

The liquid lubricant may, with advantage, contain a volatile liquid,which may or may not itself act as a lubricant for the rubber but whichhas a boiling point sufficiently low to appreciably volatilize at thetemperature generated by running of the tire in a deflated or partlydeflated condition. In this way the volatile liquid functions topartially re-inflate the tire and so reduce the high stresses generatedin the sidewall due to the deflated or substantially deflated condition.Heat build up in the tire is also lowered due to the reduced contactpressure and hence reduced frictional forces between the interior tiresurfaces. The volatilizing of the volatile liquid also assists thedissipation of heat over the entire tire and rim surface. The volatileliquid has a vapor pressure at C above 200 mm. of mercury and may have aboiling point below for example C but preferably not below, for example70 C in order that the liquid may be readily handled and not volatilizedappreciably during normal running of the tire.

The volatile liquid, may itself be used to form the basis of thelubricant, e.g. an aqueous gel, although it is then particularlypreferable to include in the lubricant some puncture sealing material inorder to at least partly seal a puncture occuring in the tire tominimize the rate at which lubricant is lost from the tire.

Preferably the liquid lubricant containing a volatile liquid comprises ahigh boiling point lubricant, e.g.

glycerol, and a volatile liquid which need not necessarily have goodlubricating properties, e.g. water, so that if all the volatile liquidis lost as vapor from the tire the high boiling point lubricant remains.The liquids may or may not be miscible with each other.

In the case of liquid lubricants containing water as the volatile liquidviscosities in the range 10,000 to 200,000 centistokes, and goodlubricant properties can be achieved by the use of gelling agents suchas those available under the trade names Natrosol, Polysteric EN4 andCarbopol. Viscous liquid lubricants such as gelled water-basedlubricants have the added advantage that they assist in sealing apuncture at least against the low, e.g. 4 p.s.i. pressures produced byvapor pressure inflation.

When the lubricant contains a volatile component it is most desirablethat the lubricant should be capable of sealing the puncture. Thus theliquid lubricant may have incorporated therein a separatepuncture-sealing or reducing material, for example, chopped cotton,wool, asbestos or synthetic fibers, e.g. of 0.000] inch diameter andabout 0.1 inch long which acts to form a matted barrier over a punctureand is carried into position by escaping inflationary air .a'nd/orlubricant.

A liquid lubricant based on an aqueous gel may contain, for example, afreeze point lowering agent such as ethylene glycol or glycerol andagents to increase the lubricating power such .as molybdenum disulphide,disoersable graphite powder and/or wetting agent or detergent such asTeepol.

It may be advantageous for the liquid lubricant to have a formulationwhich enables the lubricant to be frothed or foamed by the violentagitation caused by rotation of the tire/ wheel assembly. The foamedlubricant is spacially dispersed throughout the interior of the tireensuring that lubrication in all regions of the tire is maintained. Suchfoaming may be obtained by use of a detergent in a lubricant containingwater. A defoaming agent may also be used in the lubricant compositionto control the extent of foaming, or if desired, prevent foaming.

A dispersant may be used when fibers are incorporated in thecomposition.

The total amount of liquid lubricant in the tire is a minor proportionof the total volume of the tire, being appreciably less, for example,that the large volume of water used as ballast in agricultural andsimilar type tires which as a major proportion e.g. $43, of the interiorvolume of the tires. Such large volumes in the present invention wouldbe quite impractical since they impair the running properties of thetire, create high rolling resistance and prevent the tire being used atanything other than low speeds. In the present invention the amount ofliquid lubricant depends upon the lubricant used and the internalsurface area of the inflation chamber of the tire but for example in a185/60-13 radial ply car tire of internal volume approximately 28 litersthe total amount of lubrication will generally be at least 75millimeters but preferably less than e.g. 1 liter since above thisvolume the liquid is becoming undesirably heavy and bulky. Thiscorresponds to between 105 and 1,300 millimeters of lubricant per squaremeter of internal surface area of the tire.

In the case of a lubricant containing a volatile component sufficientvolatile component should preferably be present to generate in a volumeat least 4 times that of the inflation chamber of the tire a pressure ofat least 1 p.s.i. at a temperature of for example, 68 C. For Example inthe tire mentioned above using water as a volatile component at least 5millimeters of water should be used, although a considerably largervolume would generally be used to ensure a rapid increase in pressure inthe tire and allow for possible losses.

The liquid lubricant may be taken from a wide range of classes ofcompounds which are lubricants for rubber to rubber interfaces, forexample:

Animal oils Vegetable oils e.g. arachis, castor, linseed, olive,

palm, rape, turkey red.

Alcohols e.g. n-octanol.

Esters e.g. diethyl sulphate, methyl caprylate.

Silanes Hexafluorobenzene Soaps (e.g. sodium stearate) Alkalis (e.g.sodium hydroxide in weak solutions).

. 6 Some examples of specific compounds which may be used are soidumcarboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropylcellulose, silicone oil, glycerol, propylene glycol, Teepol (a detergentcommercially available from Shell), Hederol (a detergent commerciallyavailable from Proctor and Gamble), or mixtures thereof.

Examples of liquid lubricants containing a volatile component aresolutions of detergents e.g. Teepol in water, aqueous gels containinge.g. hydroxyethyl cellulose, with or without a high boiling point suchas glycerol, and mixtures of polyglycols or glycerol with water.

In addition to the puncture sealing and other additives previouslymentioned the liquid lubricant may contain other substances such asantioxidant, to prevent oxidative attack on the lubricant, bactericide,wetting agent and viscosity index improver ro broaden the range oftemperatures at which the lubricant has a satisfactory viscosity.

In order to minimize the weight of lubricant required and anydetrimental effects on the balance of the wheel/tire assembly the liquidlubricant preferably has a relatively low specific gravity e.g. aspecific gravity less than 1.4.

In order to maintain a degree of lateral stability even when deflated,the tire preferably has a fairly low aspect ratio e.g. 30 percent topercent and preferably 55 percent to 70 percent and the width of thetire tread is preferably greater than the width of the wheel rimmeasured between the flanges. If desired a tire having a cantileversidewall construction may be used e.g. that described in UK. Patentapplication No. 26702/70. The wheel rim upon which the tire is mountedis preferably a flat or substantially flat base rim without a well intowhich the tire beads can fall if they are displaced from their seats.

Two suitable types of rim which can be used are split rims, where therim is divisible to permit mounting of a tire thereon and axiallycompressed rims which are rims produced initially with a well, the wellbeing closed by axial compression after the tire has been mountedthereon, the latter type is shown in the accompanying drawing. When therim has no well, if the beads become displaced from their seats in theground contact area of the tire it is possible for them to be returnedto their correct positions by the forces generated during rotation ofthe wheel in normal straight ahead driving although means for positivelyretaining at least the laterally outer bead in its seat may be providedif desired. If a well-base rim is used, means are provided for retainingthe beads in their seats, e.g. a bead spacer ring or removable studs orprojections on the wheel rim.

Two particular examples of carrying out the invention will now bedescribed with reference to the accompanying drawing of a cross sectionof a tire I mounted on a wheel rim 2 and containing liquid lubricant 3.

Two gelled solutions of a water-based liquid lubricant were made up asindicated in Table l below:

TABLE I 5 ml. 95 ml.

5 ml. 95 ml.

5 disulphonate active made by Geigy). 5 ml. 5 ml.

Asbestos (Canadian Group 7 0-0-0- l6 (Floats)-very short low grit 7T.F.l. supplied by .Iohns-Manville) 2 g. 2 g.

500 millimeters of this lubricant was introduced into the inflationchamber of a pneumatic tire (size 185/60 X 13) mounted on a 3.50-13wheel rim (see drawing).

When a tire lubricated by means of the liquid as described above isdeflated or substantially deflated, opposite parts of the'interiorsurfaces of the tire or tire and wheel assembly come into contact andthat part of the load of the vehicle which is supported by the tire andwheel assembly is carried by those surfaces, substantial relativemovement taking place between them.

However, since the contacting surfaces are lubricated, the coefficientof friction is very low and little heat is generated, insufficient'tocause structural damage or changes to the tire which might cause a rapidnoticeable deterioration in the control of the vehicle. The vehicle onwhich the wheel and tire were mounted was thus enabled safely to travelsubstantial distances e.g. 30 or more miles at a reasonable speed, e.g.4O m.p.h., a replacement tire and wheel assembly eventually beingfitted.

An example of a liquid lubricant comprising glycerol as a high boilinglubricant and water as a volatile component is given below in Table II.

TABLE H Water 70 ml. Glycerol 30 ml. Natrosol 1250 HHR. 2 gm. l-lederol(detergent made by Proctor 8: Gamble) 1 ml.

A 185/60-13 radial ply tire containing 300 millimeters of this lubricantwas run under 400 lbs load against a rotating drum at 50 m.p.h. and thedrag generated by the tire i.e. its resistance to rotation was measured.The initial drag was 35.6 lbs but this value reduced steadily over the10 minute run to a final figure of 20.1 lbs. After the 10 minutes thetire was found to be inflated to 3.5 psi.

Various further tests were performed using similar tires on the sametest rig. in these tests however, the tires were run at 30 m.p.h. andthe temperatures generated in the shoulder of the tire were measuredafter 10 minutes and 20 minutes. To obtain a strict comparison betweenlubricating properties in these further tests care was taken to ensurethat the tire did not become inflated.

Firstly, a series of tests was performed to investigate the effect ofvarying the amount of lubricant. Table III below gives the resultsobtained using as lubricant a polyalkylene glycol (availablecommercially as UCON oil) having a viscosity of 433 centistokes.

Table IV below gives the results obtained using as lubricant a 50/50mixture of the polyalkylene glycol used in the tests in Table I andwater.

Table V below gives the results obtained using as lubricant theglycerol/aqueous gel lubricant whose formation is given above.

Centistokes at 38C 6 300 c.c. UCON/433 120 135 21 200 c.c. UCON/433 1 17135 19 125 c.c. UCON/433 120 140 19 50 c.c. UCON/433 120 140 19 TABLE IV300 c.c. UCON 433/Water (50/50) 120 20 200 c.c. 130 22 125 c.c. 140 2550 c.c. 140 26 TABLE V Volume of Type/Viscosity Temperatures (C) afterlubricant Centistokes at 38C 10 mins. 20 mins. Ambient 300 c.c.Water/Glycerol/Nitrosol/Hederol l00,000 90 l 10 18 (70/30) 200 c.c. 108122 20 c.c. 115 125 22 50 c.c. 125 135 22 It will be seen that in eachcase the temperature after 20 minutes is considerably higher than thatafter 10 minutes and that the temperature rises furthest when thesmallest amount of lubricant is used.

Secondly a series of tests was performed to compare the lubricantproperties of various liquid lubricants, water being included forcomparison. Similar tires run at the same speed and load as in the firstseries of tests but each tire contained 200 millimeters of a differentlubricant. The results of this series of tests are given below in TableVI.

TABLE VI Type Viscosity Centi- Temperature (C) after Stokes at 38C 10mins. 20 mins. Ambient Glycerol 224 118 123 25 Propylene Glycol 46 1105115 26 Silicone oil 470 105 125 23/24 Silicone oil 20 l 17 22 Water 0.7100 150 20 UCON oil (polyalkylene glycol) 433 117 19 It will be seenthat water initially maintains a low temperature which after 10 minutesis as low as or lower than the other lubricants but after a certainlevel of temperature in the tire is reached the temperature begins torise very rapidly so that after 20 minutes the temperatures of thewater-containing tire has risen to C which is approaching tire failure.

If lubricant should leak onto the road surface, when it is water-basedor miscible with water it can be washed away by rainfall, so as toprevent the build-up of a hazard to other road vehicles by the reductionof the coefficient of the road surface below a safe level.

When a liquid lubricant containing a volatile component is used it maybe desirable to include in the wheel rim or tire a safety pressurerelease valve or other device e.g. a safety plug to prevent the tirefrom becoming over-inflated. However, as the increasing internalpressure increases the boiling point of the liquid lubricant, it isadvantageous to design the lubricant so that its boiling point, at themaximum permissible tire inflation pressure has increased to above themaximum permissible generated temperature, so that boiling of thelubricant stops before the tire can become severely over-inflated.

In the present invention the liquid lubricant may be inserted directlyinto the inflation chamber of the tire before the tire and wheelassembly is sold, preferably, however, the lubricant is provided in anenclosing means which releases the lubricant into the tire upondeflation as described in U.K. Patent application No. 30027/70 (interiorlubricant container). Alternatively the lubricant may be injected intothe tire after deflation as described in UK. Patent application No.30028/70. The invention may also be used with the inventions describedin UK. Patent application Nos. 30029/70, 30030/70, 30031/70, 30032/70and 07024/71.

The invention applies to tire and wheel assemblies in which the tire canbe removed from the rim or, altematively, when the tire is not removabletherefrom ie the two form a permanent assembly, for example, when therim is swaged over the tire beads after assembly of tire and rim.

We claim:

l. A pneumatic tire and wheel assembly having a single inflation chambercapable of being run in a deflated condition comprising:

1. a wheel having a wheel rim with a pair of opposed annular flanges;

2. a pneumatic tire having a tread portion whose width is greater thanthe width of the wheel rim measured between the flanges;

3. a flowable liquid lubricant which, when the assembly is used with thetire in a deflated condition, will facilitate relative movement ofcontacting interior surfaces of the tire.

2. The pneumatic tire and wheel assembly of claim 1,

in which the liquid lubricant is miscible'with water.

3. The pneumatic tire and wheel assembly of claim 1, in which the liquidlubricant does not freeze at temperatures above C.

4. The pneumatic tire and wheel assembly of claim 1, in which at leastone liquid component of the lubricant has a vapor pressure of less than50 mm of mercury at 140 C.

5. The pneumatic tire and wheel assembly of claim 1, in which the liquidlubricant includes some puncture sealing material in order to at leastpartially seal a puncture occuring in the tire.

6. The pneumatic tire and wheel assembly of claim 1,

in which the liquid lubricant has a specific gravity less than 1.4.

7. The pneumatic tire and wheel assembly of claim 1, in which the tirehas an aspect ratio between 30 percent and percent.

8. The pneumatic tire and wheel assembly of claim 7, in which the aspectratio of the tire is in the range 55 percent to 70 percent.

9. The pneumatic tire and wheel assembly of claim 1, in which the wheelrim upon which the tire is mounted is substantially flat based without awell into which the tire beads can fall if they are displaced from theirseats, the rim being divisible to permit mounting of the tire thereon.

10. The pneumatic tire and wheel assembly of claim 1, in which the wheelrim upon which the tire is mounted is produced initially with a well topermit mounting of the tire on the rim, the well being closed by axialcompression after the tire has been mounted thereon.

11. The pneumatic tire and wheel assembly of claim 1, in which theliquid lubricant contains a volatile liquid which has a boiling pointsufficiently low to appreciably volatilize at the temperature generatedby running of the tire in a deflated or partly deflated condition.

12. The pneumatic tire and wheel assembly of claim 1, in which the totalamount of lubricant in the tire is in the range of to 1,300 mls oflubricant per square meter of internal surface area of the tire.

13. The pneumatic tire and wheel assembly of claim 1, in which theliquid lubricant has a formulation which enables the lubricant to befrothed or foamed by the violent agitation caused by rotation of thetire and wheel assembly.

14. The pneumatic tire and wheel assembly of claim 1, including adeforming agent to control the extent of foaming.

15. The pneumatic tire and wheel assembly of claim 1, in which the rimhas an area of excess material bent so as to leave the rim substantiallywithout a well between the flanges.

Patent No 3 759 829 Inve LESLIE VERNON POWELL, ET AL It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

(SEAL) Attest:

McCOY M. GIBSON, JR. Attesting Officer UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTION Dated June 19,1973

"r0" to to Column LP, line 1 T, change Patent application 26702/70"Column 4, line 29, "U. K.

should read co-pending application No. 1 +5,61O filed 1 Column 5, lines65 to 6 T, formulation Column 7, lines 2-5, U.K. Patent Application No.5002'7/70" should read co-pending application No. 150,627 filed June 7,1971 Column 7; lines 5-6, U.K. Patent application No. 50028/70" shouldread co-pending application No. 150,562 filed June 7,1971

Column 7, lines 7-9, "U.K. Patent application Nos. 50029/70, 50050/70,50051/70, 50052/70 and O'7O2 +/71" should read co-pendin applicationsNos. 150,628, 150,561, 15O,56 150, 560 all filed June 7,1971 and 252,850filed March 8, 1972 change "formation' to Signed and sealed this 6th dayof August 197A.

C. MARSHALLDANN Commissioner of Patents Foam P0-1050 (10-63) USCOMM-DC60376-1 69 us. GOVERNMENT rmmms ornc: I9" 0-366-534.

1. A pneumatic tire and wheel assembly having a single inflation chambercapable of being run in a deflated condition comprising:
 1. a wheelhaving a wheel rim with a pair of opposed annular flanges;
 2. apneumatic tire having a tread portion whose width is greater than thewidth of the wheel rim measured between the flanges;
 3. a flowableliquid lubricant which, when the assembly is used with the tire in adeflated condition, will facilitate relative movement of contactinginterior surfaces of the tire.
 2. a pneumatic tire having a treadportion whose width is greater than the width of the wheel rim measuredbetween the flanges;
 2. The pneumatic tire and wheel assembly of claim1, in which the liquid lubricant is miscible with water.
 3. Thepneumatic tire and wheel assembly of claim 1, in which the liquidlubricant does not freeze at temperatures above -20* C.
 3. a flowableliquid lubricant which, when the assembly is used with the tire in adeflated condition, will facilitate relative movement of contactinginterior surfaces of the tire.
 4. The pneumatic tire and wheel assemblyof claim 1, in which at least one liquid component of the lubricant hasa vapor pressure of less than 50 mm of mercury at 140* C.
 5. Thepneumatic tire and wheel assembly of claim 1, in which the liquidlubricant includes some puncture sealing material in order to at leastpartially seal a puncture occuring in the tire.
 6. The pneumatic tireand wheel assembly of claim 1, in which the liquid lubricant has aspecific gravity less than 1.4.
 7. The pneumatic tire and wheel assemblyof claim 1, in which the tire has an aspect ratio between 30 percent and75 percent.
 8. The pneumatic tire and wheel assembly of claim 7, inwhich the aspect ratio of the tire is in the range 55 percent to 70percent.
 9. The pneumatic tire and wheel assembly of claim 1, in whichthe wheel rim upon which the tire is mounted is substantially flat basedwithout a well into which the tire beads can fall if they are displacedfrom their seats, the rim being divisible to permit mounting of the tirethereon.
 10. The pneumatic tire and wheel assembly of claim 1, in whichthe wheel rim upon which the tire is mounted is produced initially witha well to permit mounting of the tire on the rim, the well being closedby axial compression after the tire has been mounted thereon.
 11. Thepneumatic tire and wheel assembly of claim 1, in which the liquidlubricant contains a volatile liquid which has a boiling pointsufficiently low to appreciably volatilize at the temperature generatedby running of the tire in a deflated or partly deflated condition. 12.The pneumatic tire and wheel assembly of claim 1, in which the totalamount of lubricant in the tire is in the range of 105 to 1,300 mls oflubricant per square meter of internal surface area of the tire.
 13. Thepneumatic tire and wheel assembly of claim 1, in which the liquidlubricant has a formulation which enables the lubricant to be frothed orfoamed by the violent agitation caused by rotation of the tire and wheelassembly.
 14. The pneumatic tire and wheel assembly of claim 1,including a deforming agent to control the extent of foaming.
 15. Thepneumatic tire and wheel assembly of claim 1, in which the rim has anarea of excess material bent so as to leave the rim substantiallywithout a well between the flanges.